1. Field of the Invention
The present invention relates to an MRI apparatus for taking MRI images of a subject, and a bed apparatus on which a test body is placed as the subject of the MRI images.
2. Description of the Related Art
MRI (Magnetic Resonance Imaging) apparatus is a medical imaging apparatus such that when the applied magnetic field is applied to a test body placed on the bed apparatus in the static magnetic field, an excitation magnetic field (RF magnetic field) is applied from an excitation magnetic field coil (transmitter RF coil) to obtain nuclear magnetic resonance signals (MR signals) with a nuclear magnetic resonance signal coil (receiver RF coil), and the MRI images (cross-sectional images) of said test body are reconstituted on the basis of the obtained nuclear magnetic resonance signals (MR signals).
If tomography is carried out using such an MRI apparatus, many RF (Radio Frequency) coils need to be placed in order to obtain a high-quality image. Hence, in capturing images of the test body covered with a unit (sheet) arranged with RF coils, the test body is covered with the unit's many RF coils, Therefore, the test body feels the massive weight and there is a loss of comfort during the capturing of the images.
So, reducing the weight of the coils was attempted, in order to reduce the weight placed on the test body. But there is a limit to reduce the weight of the coils, due to the increase of RF coils accompanying multichannelizing and the corresponding increase in electrical components involved.
For this purpose, an MRI apparatus has been proposed, consisting of placing a hard wagon-head shaped board (hereinafter called “forma”) on the test body and placing a sheet arranged with receiver RF coils on it (for example, refer to Japanese published unexamined application No. 09-075323.) Also there is an MRI apparatus to reduce the weight on the test body by using hard materials for the unit that is arranged with RF coils, in order to have a shared forma.
However, in configurations where the RF coils require a forma (a member which supports RF coils by adjusting them to the placement site), aside from the unit that is arranged with RF coils, a set of two steps is needed, namely a big forma to cover the body and a sheet with RF coils. And in cases where the forma and the unit that is arranged with RF coils are shared, the unit that is arranged with RF coils, which is shared with the forma, becomes larger and heavier, and it is difficult for the operator to handle it. In addition, if the test body is large, it is difficult for the operator to observe the location of the forma across the test body, which is placed on the bed apparatus, on the opposite side from the operator.